Railway traffic controlling apparatus



O t 3, 1942- R. A. M CANN RAILWAY TRAFFIC CONTROLLING APPARATUS FiledNOV: 5, 1941 .m W m m .A M w a H m B Patented Oct. 13, 1942 UNITEDSTATES PATENT RAILWAY TRA FIC GQNTRQLLING. APPARATUS 3 Claims.

Myinvention relates to railway trafiic controlling apparatus, andmoreparticularly; to. the con trolof an, approachlocking stick relayijor' electrically interlocking a track switch with therailway signalswhich. sorerntraflic movements over the;

In. the art of railway signaling, it is the pro-- vailing practice toguard against the inadvertent operation of a track switch when a trainisapproaching; or passing over the switch by the pro vision ofa system; ofrelays. embodying suitable approach.v and. detector locking asillustrated, for example, in Letters. Patent Of the United States No.1,959,072,. granted May 15, 1934, to Herbert A. Wallace, for Railwaytraffic controlling apparatus. or in LettersPa-tent of the UnitedStates, No. 2,141,074,, granted December 20, 1938-, to: Henry S- Young,for Railway trafiic controlling apparatus.

A feature of; such systems is the provision of an. approach; lockingstick relay for eachsignalor group. of signals, which relay must be:energized order to. permit the operation of any switch included in aroute governedby the signal. Usually the control of. the approach lockins relay by the signals is effected through the medium of a back. lockor signal indication re-- lay, such as the relay L5 of Wallace, or relayZRGP of Young, controlled over a circuit. including; contacts closed bythe home signals in the; stop position, and it these signals include amainline signal governing; high speed traffie move:--

men-ts, the back lock circuit also includes line.

wires extending along the trackway to the-corre-- sponding distant.signal andincludes contacts: closed only when the distant signaldisplays.- a restrictive indication;

Myinvention is an improvement upon thiscircuit arrangement, comprisingthe provision of entirely separate back lock circuits for the home:

anddistant signals.

One.- object of, my; invention is to: enable the;

approach, locking relay to be; held, energized as. long as; conditions;are proper, by means of local circuits which do notv extend beyond thelimits. of the interlocking plant, and; which therefore;

are not dependent. upon'the conditionof the linecircuit: only, therebypreventing the approach locking relay from releasing to. render; thelocking effective with respect to conflicting, routes, due to a. failureoi the line circuit leading to the distant signal occurring at a timewhen the home signals are at stop. and consequently no question. of. safy or oper tio s nvol d- 1 shall. describe one form of apparatusembodying my invention, and shall then point out the novelfeaturesthereof in claims.

Referring to the accompanying drawing; the. track dia r t he. pni dis -ma s ret h f ytrack o w ch -mt n nisa p ed. the stretch. being: dividedthe: us lnranner' by insulated joints to form th track sections l 'I-.,.MIT and ZOE-leach; ofwhich-is provilie e with the usual; trackcircuithav ng; atrack, battery; as. s and w essmd nsla n mbered t ac relaySection III constitutes a detector section includingthe;traclgswitchtSW, over which t-raflicmovements from left; to. right. aregoverned by the home: signals 23A and 23B, and from. right: to left bythe; home signals and- Re y ZLGP is t a k 9 1 si nalin ication. rel yrepa g hes onr s tion e1 them s na A an Z B. an as how. ne ma v energizedover. a circuit. extending from one-ter;-- minal Bof-a suitable localsource of current ever contacts 3 and- 4, closed, when. signals and ZLBrespectively indicate stop;, tl 1ro.1.1ghv the; wind-- ms of re y 1 GBeer: erm;i alor t samesource.

It will e d r oe a thes ie alsare u ject to the usual manual controrbythe operation of a signal lever- 2V to left or right. to piclr up asignal control: relay. ZLHR. or. 2RH-R, as. shown... Signal: H] isanautomatic blocls, signal comprising the distant,- signal. for signal 2%,and i con.- trolled inv the usual. manner over a line circnit. includingfrom contacts of thetrack. relay HERE. and extending to, terminals 3-and-C. ofthe local; source of current over the pole: changer con tacts5. controlled1 by signal Relay. IilRI-IGP- is the additional indication.rela provided: in ac cordance: withmyinvention and normallyenergizedover a circuit, extending from. one terminal Bill. of. a local.source of current atthe location of signal to, over. contact ,6 closedonly when signal H], is at stopor caution, through the. winding of relayIBRHGB to the, other. terminal CID oithesame source.

Relay is the usualx approaeh. relay and is; normally energized overaline circuit. extending over front contacts; oi-the track; relays IDTR.and R- o: t er i a B20 nd C20 f; a l c source ofcurrentat the location;ojrelay R ay S AS s; the: ppro ch lockin relax associated with signals2L A,. and tilt. and is normally held energizedotier anstickcircuitextending from: terminal B- over contacts. 1* and- B: ofrelays, Z-LHR. and Z-LGP, front contact. 9 and winding; of relay ZLAS.to terminal: G), as shown. r y he.- drawins I. have: shown in; detailonly those. circuit relating: to traflie movements from right to left;but itwill. be understood. that generally similar circuits: ar reuiredior. the. op,

posite direction. That is, relay 2RAS is an approach locking relay likeZLAS and similarly controlled by the signals 2RA and ZRB. It is to beunderstood that the detector section IT is representative of a typicallayout, and. that in practice, additional detector sections and trackswitches may be located between the opposing home signals shown. a

The track switch ISW is provided with the usual power operatingmechanism comprising the switch machine ISM, which as indicateddiagrammatically is controlled by a polarized switch control relay IWR.Relay IWR is manually controllable in accordance with the position of aswitch lever IV, over a circuit including front contacts of the approachlocking relays ZLAS and ZRAS and of the detector section track relayITR.

Assuming the apparatus to be in its normal condition as shown, it willbe readily apparent from the drawing that if lever 2V is moved to theleft to pick up relay ZLHRJZhe opening of contact 1 will cause theapproach locking relay ZLAS to release, thereby completing a circuit forclearing signal ZLA, analogous to the signal circuits of the Youngpatent above referred to, this circuit extending from terminal B atfront contact [9 of relay ZRAS, over other contacts, not shown, asindicated by the legend Network, back contact ll of relay ZLAS, frontcontacts l2 and I3 of relays ITR and ZLHR through th operating mechanismfor signal 2LA to terminal C. Signal 2LA therefore clears and by openingcontact 4 and reversing the pole changer 5, releases relay ZLGP and alsocauses signal In to assume the clear position. Relay 2LGP upon releasingopens contact 8 in the circuits for relay ZLAS, while signal ID in theclear position opens contact 6 releasing relay HJRHGP to open contact I4in the pick-up circuit for relay ZLAS. Contacts I5 and I6 of relay ZLASbeing open, relay IWR is held deenergized to lock switch ISW in thenormal position, as shown.

Assume now that the signal lever 2V is restored to normal, releasingrelay ZLHR to restore signal 2LA manually to stop. The closing ofcontact 4 by the signal causes relay ZLGP to pick up, and the operationof contacts 5 causes signal I!) to again assume the caution position topick up relay I URI-1GP. If sections HIT and 20T are unoccupied so thatrelay LAR is picked up to close its contact H, a pick-up circuit forrelay ZLAS will be completed from terminal B over contacts 1, 8, l4 andI! through relay 2LAS to terminal C. Relay ZLAS may also be picked up inthe usual manner after a time delay by the operation of a time elementrelay ITE, in the event relay LAR is not energized, or may be picked upautomatically over back contact l8 of relay ITR if a train governed bysignal 2LA enters the detector section IT, but since each of the pick-upcircuits includes contact [4 of relay IORHGP, it will be clear that thereturn of signal 10 to stop or caution is fully checked, and that relayZLAS cannot become energized unless signal HJ displays a restrictiveindication, as in the systems of the'prior patents hereinbefore referredto. It will also be clear that after relay ZLAS is once picked up it isheld energized over the stick circuit including contacts 1, 8 and 9only, so that relay ZLAS is prevented from becoming released andconsequently the switch ISW is free to be operated even though relayIURHGP is released, as might occur due to a failure of the back lockline circuit, as already explained. The reliability of the system isthereby increased, since the remaining circuits involved are to a largeextent local.

Although I have herein shown and described only one form of apparatusembodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track including a track switch,a home signal for governing trafi'ic movements over said switch, anapproach locking relay, circuits for controlling the operation of theswitch including front contacts of said approach locking relay, adistant signal for governing the movement of traific approaching saidhome signal, a plurality of pick-up circuits for said approach lockingrelay each including a first contact closed only when said home signalindicates stop and a second contact closed only when said distant signaldisplays a restrictive indication, and a stick circuit for said approachlocking relay including said first contact but not including said secondcontact.

2. In combination, a stretch of railway track including a detectorsection containing a track switch and an adjoining approach section, anapproach locking relay, circuits for controlling the operation of thetrack switch including front contacts of said approach locking relay, ahome signal for governing the movement of traflicfrom said approachsection into said detector section, a distant signal for governing themovement of traflic approaching said home signal in said approachsection, circuits controlled by said home signal arranged to cause saiddistant signal to display a restrictive indication when said home signalindicates stop, a first repeating relay arranged to be energized onlywhen said home signal indicates stop, a second repeating relay arrangedto be energized only when said distant signal displays a restrictiveindication, pickup circuits for said approach locking relay eachincluding front contacts of both said repeating relays, and a stickcircuit for said approach looking relay including its own front contactand front contacts of only said first repeating relay.

3. In combination, a stretch of railway track including a track switch,two home signals for governing the movement of traffic in a givendirection over said switch in its normal and reverse position,respectively, an app-roach locking relay, circuits for controlling theoperation of said switch to normal and reverse effective only when saidapproach locking relay is energized, a distant signal in said stretchfor governing the movement of trafiic approaching said switch in saidgiven direction, a repeating relay associated with said approach lockingrelay, a line circuit extending to said distant signal for energizingsaid repeating relay including contacts closed only when said distantsignal displays a restrictive indication, pickup circuits for saidapproach locking relay including contacts closed only when said homesignals indicate stop and also including a front contact of saidrepeating relay, and

a stick circuit controlled by said home signals effective to maintainsaid approach locking relay energized regardless of the condition ofsaid repeating relay.

RONALD A. McCANN.

